Apparatus for purifying liquids.



PATENTED JUNE 30, 1903.

G. D. MITCHELL. APPARATUS FOB. PURIFYING LIQUIDS.

APPLICATION FILED MAY 31, 1901.

2 SHEETS-SHEET 1. A

N0 MODEL.

No. 732,208. PATEN'IED JUNE 30, 1908. G. D. MITCHELL.

APPARATUS POR PURIFYING LIQUIDS. APPLIOATIONIHLBD xu a1, 1901. No nonni.. z snnz'rsfsnn'r z.

HH!IIHVIHHIIIHHIIIIIIIIHIIVM GARRYT D. MITCHELL, OF

Patented June 30, 1903.

PATENT OFFICE.

CHELSEA, MASSACHUSETTS.

APPARATUS FOR PURIFY'ING LIQUIDS.

SPECIFICATION forming part 0f Letters Patent N0. 732,208, dated June 30, 1903.

' Application led May 31, 1901 .To @ZZ whom,A it may concern:

Be it known that I, GARRYT D. MITCHELL, of Chelsea, county of Suffolk, and State of Massachusetts, have invented an Improvement in Apparatus for Purifying Liquids, of which the following description, in connection with the accompanying drawings, is a speciiication, like letters on the drawings representing like parts.

, The present invention relates to a filtration system, and is mainly intended for use in the filtration of water supplied to cities and towns for drinking purposes, although the same system may be used for the purification of sewage, if desired, in order that the water from the sewage may be discharged into streams without polluting the water therein. l

The system may be generally described as consisting of means for subjecting the Water or sewage, first, to a process of sedimentation to separate the water from the heavier and lighter impurities which seek their natural levels, and, secondly, to a system of filtration in which the water or sewage which has been mainly separated from impurities which are not in actual solution is subjected to bacterial action to get rid of poisonous matter which is held in solution.

The present invention does not relate, broadly, to the system above described, which is not new, but is embodied in certain details of construction and arrangement of the plant which increases the efficiency thereof and lessens the waste, the invention, as stated, being mainly intended to be applied to the filtration of water for drinking purposes.

The system in which the invention is embodied comprises a series of tanks for the purification of the water by sedimentation, the water flowing from one tank to the next at a point intermediate between the floating imv purities and those which sink to the bottom and finally passing through a suitable iilter (which is preferably a body of coke and in` tended to take up such solid matter as may remain in the water) into a flushing-tank, which is so arranged as to be rapidly fiushed or discharged at intervals, the entire contents of the said tank being thus discharged at once and distributed over a large area of filterbeds, this giving a better result than is obtained by a continual slow discharge. The

. Serial No. 62,510. (No model.)

flushing is controled by a Siphon or other automatic flushing device, which opens communication between the fiushing-tank and a pipe or duct from which lead a series of troughs extending over the several sections of the filter-bed, so that the Water from the tank is all discharged at once and distributed over substantially the entire surface of the lter-bed, so that the whole of the same is utilized at one time. The filter-bed is arranged in accordance with the invention with a series of4 aerating-passages near the bottom and at points intermediate between the bottom and the top and is placed under cover, the roof over the same, however, being transparent, so that the filter-bed is exposed to the suns rays, like a hot-bed, whereby the bacterial action is aided, while the aerating pipes or tu bes,throu gh which air is preferably drawn by forced draft, supply sufficient oxygen to complete the action. The several sedimentation-tanks are arranged so that any one can be out offfrom the series temporarilyfor cleaning purposes, and a further feature of the inventionV consists in providing each tank with mea'ns'for drawing off the purer water therein and discharging the same over the filter-bed in order to avoid the waste of a large amount of substantially pure water when the -tank is to be cleaned.

Figure l is a general plan view of the system embodying the invention, the Walls of the inclosing building being shown in section. Fig. 2 is a transverse section on the line :r2 of Fig. l, and Fig. 3 is a section transverse to the plane of Fig. 2 on line m3 of said Fig. 2.

As herein shown, the apparatus is provided with a series of sedimentation-tanks o, to any of which the water to be purified is admitted from a sluiceway b through a gate a2, and the contents of the tank pass throughraV passage a3 near the opposite end into the next tank in use, each tank being shown as having two of such passages a3, one at each end, the ones opened being always diagonally opposite to each other, so as to produce a flow of water across each tank. The passages are shown as vertical, with an inlet aso near the bottom and an outlet asl near the top, so that the water leaves each tank at a point below its level, but enters each tank near the top. The

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inlet @30, however, is somewhat above the level of the bottom of the tank, so that the heavier substances, which fall to the bottom, are trapped, so to speak, while the lighter substances, which rise to the top, arelsuspended above the said inlet, the purer water only passing into the next tank. The last tank of the series is shown as provided with a larger passage containing iiltering material a4, such as coke, through which the water passes when flowing into the flushing-tank c, where it remains until it has reached any desired level, (preferably such level as to be substantially the entire capacity of the tank,) and after it has reached such level it is rapidly discharged in any suitable way, the dischargevbeing shown as automatically controlled through the agency of a Siphon c2. The said Siphon connects with a pipe or sluiceway d, from which extend a series of troughs d2, each over the surface of the filter-bed e, each trough being controlled by a gate or valve d3. The filter-bed is built up in the usual way of broken stone, gravel, and sand and is shown as divided by partitions d4 into several seciions,it being practicable to control the discharge of water by the valves d3, so that any section can be allowed to rest for cleaning and purification. Extending through the body of the filter-bed at two or more levels are aerating-passages e2, shown as invertedtrough-shaped Yducts supported in the material of which the iilter-bed is built up, and these ducts are supplied with fresh air through an inlet e3, the air being drawn through the ducts into an outlet-pipe e4, which Vpasses into the chimney e5, which may be provided with a fan or blower, if necessary, to produce a forced draft, or may constitute the draft-passage for a furnace, which puries and deodorizes the air as it passes up the chimney. The said ducts are laterally open to the filtering material, being shown as supported upon the larger pieces of rock, so that the impure gases can enter the ducts and mingle with the air owing through the same, the result being that the gases are sucked up by the air and carried away. rIhe lateral opening, moreover, is shown as underneath, so that the water trickling down is shed by the ducts, while the air travels through the ducts over the Water below, carrying away the rising gases.

The filter-beds are arranged under a glass roof and are inclosed in the building, the heat of the sun heightening the bacterial action, while the flow of air through the aeratingpassages affords a continual supply of fresh oxygen.

The tanks a are so arranged that any one of them can be cut ont for cleaning purposes without interfering with the action of the others, so that the plant can remain in continual .operation without being shut down for the purpose of cleaning 'the tanks or resting the filter-bed. The sluiceway b for this purpose has an outlet a2, leading to each of thetanks, each outlet being supplied with a gate or valve, so that if any tank is shut off from the rest by closing the communicating passage a3 the water can flow around the said tank through the sluiceway and into the next tank of the series. The said slniceway is also provided with gates or valvesy b2 b3 b4 to control the flow of water, and each passage a3 has a gate @32, controlling an opening into the sluiceway, so that by manipulating the valves the water can pass through the sluiceway around any tank.

In order to avoid wasting the large amount of comparatively pure'water in any tank which is to be cut out and emptied for cleaning purposes, each tank `is provided in accordance with the invention with an outlet a5, which opens directly into the dischargepipe d, with an inverted trap a7, the inlet to which is far enough above the bottom of the tank to leave all the sediment in the said tank,while the bend of the trap is sufciently high to cut off all Hoating matter, the result being that the purer water in the tank is discharged directly onto, the filter-bed, and thereby saved. To facilitate the cleaning of the tanks, each tank is shown as provided with a sloping bottom and an outlet as at the middle, the said outlet opening into a discharge-pi pe a9,toward which the impurities may be directed by those cleaning the tank. The outlet-pipe a9 is also shown as communieating' with the iiushing-tank c, so that if clean Water is Wanted inv the tank which is being cleaned it can be obtained by opening the valve in the flushing-tank and that of the tank being cleaned, so that the water from the flushing-tank in any desired quantity will back up into the 'tank which is empty.

I claim- 1. In a filtration system the combination with a series of sedimentation-tanks each having an opening into the next tankbelow the normal water-level; of a flushing-tank adapted to receive water from the sedimentation-tanks; means for rapidly discharging the water from said flushing-tank at intervals, and a filter-bed to receive the water from the said dashing-tank, as set forth.

2. In a filtration system the combination with a series of sedimentation-tanks each having an opening into the next tank below the normal water-level; of a flushing-tank adapted to receive water from the sedimentation-tanks; a filter interposed between the sedimentation-tanks and the liushing-tank and a filter-bed to receive the Water from the said fiushing-tank.

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3. In a filtration system, the combination vals; a filter-bed; and discharging pipes or troughs to distribute the water from the ushing-tank over the surface of said filter-bed, as set forth.

4.-. In a iltration system the combination with a series of sedimentation-tanks each having an opening into the next tank below the normal water-level; of a flushing-tank adapted to receive water from the sedimentation-tanks; means for rapidly discharging the water from said iiushing-tank at intervals; a filter-bed divided by partitions into separate sections; a distributing-pipe to receive water from the flushing-tank; and troughs leading from said pipe over diierent portions of the filter-bed, the said troughs being each provided with means for shutting 0E the water therefrom so that part only of the filter-bed may be used at a time.

5. In a filtration system, the combination with a series of sedimentation-tanks; of a filter to receive the Water which has been partially purified in said tanks; passages extending through the body ot' said filter at dierent levels below the surface thereof, said passages being laterally open underneath to the filtering material; and means for circulating air through said passages to carry away the gases, substantially as described.

6. In a filtration system the combination with passages through which the water iiows from one tank to another; of means for cutting out any tank of a series and passing the Water around the same through a duct or passage to the tank beyond; a iilter-bed; an outlet from each tank directly to the filter-bed, the said outlet being near the bottom of the tank and controlled by a Valve; and an inverted trap for each of said outlets, as set forth.

In testimony whereof I have signed my name to this speciication in the presence of two subscribing witnesses.

GARRYT D. MITCHELL.

Witnesses:

HENRY J. LIvERMoRE, J As. J. MALONEY. 

